Stencil printing apparatus



Oct. 27, 1931. J. FLOCKHART STENCIL PRINTING APPARATUS 2 Sheets-Sheet l x Filed March 24. 1930 INVENTOR. Jnm'LE 5 Flo C LC ILELT t u.

ATTORNEY.

Oct. 27, 1931.

J. FLOCKHART STENCIL PRINTING APPARATUS Filed March 24 1930 2 Sheets-Sheet 2 I N VEN TOR. flumkhufl James ATTORNEY. 1

Fatented Oct. 2 7, 1931 TEVUNI'TED oFFlce ja s FLocKHART, or SAN FRANCISCO, ammonia, AssIGNoaTo THE FLOCKHAR'I joo.,fmc., or sAN 'rnANcIsoo, CALIFORNIA, a. conronarrron or camromvm This invention relates to improvements in stencil printing apparatus and moreparticularly to stencil frames therefor.

' .'-The principal objectofjthe invention is 5 to provide means for stretching silk cloth stencil screens taut without wrinkling. ',Another object is to remove dlstortion 'ifrom the stencil inthe first and subsequent 'stretchings.

- A further object is to provide a frame that .lis light, compact, rigid, and easily manipujglated. Otherobjects and advantages Wlll appear'as the description progresses.

In thisspecification and the accompanying drawings the inventionis disclosed inits preferred form. But itis to be understood that itis not limited to this'for'm because it may be embodied in other forms. It is also I .tobeunderstood that in and by the clalms 20.

gcurethe invention in'whatsoever form it may Abe embodied. I 11".; In the two sheets of following the description it is desired tosedrawings: Fig. ljis a'fragmentary-plan view from ajbove'of a stencil frame constructed inaccordance with this invention, installed withq in an adj ustable' chase v or frame. I

Fig. 2 is an enlarged detail in vertical sec- ;-'tion-on the1linie-'II.II. I i

Fig. 3 is an end view detail taken at the z-point III, see arrow Fig. '1. 2:1 Fig. 4; is a detail'viewsimilar to Fig. 1 of fl acorner of the frame. Fig. 5 is an end .1 1

- Fig'. 6 is aside elevation of the same.

Fig. 7 is an enlarged detail in cross section and perspective of a simplified modification For the stencilfframe.

In detail the construction illustrated in the i drawings,'referring to Fig. 2, comprises a rectangular open rigid integral base frame. The

1 side rails1,'ofthis frame, have thebottom surilf eie Mae n i Th i frame in the bottom rails 1.,

elevationofone end of the 'mitered atthe corners; side flaps IQOILthGgHIGfi; of the screen. These i STENCIL PRINTING-APPARATUS is preferably integral, it maybe built up of separate parts properly joined. The outer side land top are milled away to leave the upstanding flange 6, having the rabbit 7 longitudinally under when thetop 5 is milled away.

1 Thetop 5 has the grooves '8 and 9 milled therein the length of the side rails 1. The port-ion of the top and outer side of the rail cut away is replaced bythe top rails 10 having the tongue 11 fitting closely within the rabbit 7. These rails are also. grooved longitudinally at 12 to aline with the grooves 8 Thecomplete f ame is composed of the four bottom rails .1 of the base frame, and four top rails 10. At the corners one end of'each top rail 10' overlaps thewidth of the contiguous bottom rail andthe end lugs. The cross Sec tion of the top rails thus assembled completes the rectangular cross section of the base frame, see Fig. 4. The tongues 11 are" cut away at 11, adjacent the corners so that the edges'of the top rails can met at 13 at their .ends, but leaving thecontinuation 10 of the 1 underside of the top rail,'see F igs. 3, 5..

' The screen 18 is applied by laying it on a flat surface and superiinposing the base frame with the bottom '2 resting upon the screen. A marginal width of screen-equal to the' height of the sidel plus the width of the top 5 and the depth of the groove 9 is allowed and thescreen cut tosizep The four corners of the screen are then cut away obliquely or This leaves four flaps are'then folded inward over the tops 5 across the grooves Sand 9.,

cut therein Q The top rails are fixed to the base frame-by the corner screws 14 14 threaded in the 4 holes 15 in thebase frame, see Figs. 1, 3 and 4.

The clamp bars 16 rest within the grooves 9 in'the base frame in front of the ends of the The clamp bars 1616 are then pushed into the grooves 99, carrying the edges of the flaps down into the grooves, see Fig. 4. The screws 17-17 are then set-up to clamp the edges of the flap-in the grooves 9. Some care should be taken in adjusting the screen area 18 to avoid distortion of the warp and woof pattern of the cloth. This can be ver easily done by proper manipulation of the aps 19.

With the clamps 16 set up tight to hold the flaps 19, the flexible rods v20 are. laid on top the flaps over the grooves 8. The top rails 10 are then fixed in position on the base frame as described, and held by the screwslA-ll at their opposite ends.

The diameter of these rods 20 extend up into the grooves 12 in their respective top rails 10. The adjusting screws 21-21, are threaded in the rails 10 at intervals and bear against the tops of the rods 20.

When these screws 21-21 are screwed down, they force the rods downward carrying a loop of the flaps 19 down into the grooves 8, to draw the area 18 of the screen taut. In actual practice these rods 20 are about three sixteenths of an inch in diameter and may be distorted by the screws 21 to affect a given area of the screen to remove slack or pull any rtion of the stencil pattern into desired reglStIy with the image to be reproduced.

One of the advantages of this'invention is that the screen stencils may be removed from the frame after use and filed away fiat. If a duplicate order is desired the screens can again be replaced in the-frame and the tightening accomplished by the screws 21, and the stencil image restored to its original registry with the master image from which it was made. Heretofore it has been necessary to leave the screen stencil in the frame, tying up "capital in inactive frames "and storage space.

Neither could the stencil image be manipulated to remove puckering or distortions that ma occur during storage.

he protection strips 2222 are added to the outer edges 40f the frame and held by the screws 2323 threaded into the top and/0r bottom rails 1l and 10 10.

Thus assembled, the stencil frame is inserted into the printing frame or chase '24:, wherein it is secured by the opposed adjusting screws 2525. These screws are useful in attaining registry of the screen frame on the platen (not shown), especially in multicolor printing where several stencils are used in producing-an image on a surface resting upon the platen. In this connection see my 00- pending application entitled Stencil frame, filed September 30, 1929, and bearing Serial Number 396,083.

The @ructure of the frame, particularly at the corners, has been specifically described, but modifications within the purview of the invention to meetvarying requirements, will be manifest to those skilled in the art, for instance, as shown in Fig. 7.

The modification shown in Fig. 7 consists of two integral rectangular frames 1% and 10m. The lower frame 100 has the channel 800 in the top thereof to receive the rods 2000.

The top frame 10% has a similar channel 1200 for the rods 20% with the adjusting screws 21m bearing thereon. The two frames are held together by the marginal screws llw at intervals and threaded in the lower frame.

The 'liaps 19% of the screen 1803 are carried over the edges of the lower frame, under the rods 20% andclamped at 1600 between the two frames by the screws'l lw. "The, slack in the flaps 19m can'be drawn taut before the screws lea are setup tight to clamp them.

The flanges 22% are formed on the top frame .l'Otv toreceive. the ends of the adjusting screws 25 in the chase 24, as described in connection with the other form of screen frame. The rod adjustment 20m and screws 21% also operate as previously described.

Having thus described this invention, What I claim and desire to secure by Letters Patmeans thereon and grooves "therein; flexible rods in said grooves and flexing means on said frame engaging said rods.

' 3. A stencil frame having parallel grooves therein; clamping bars and rods in said grooves respectively; independent adjusting means on said frame engaging said bars and rods respectively.

4:. A stencil frame having bottom rails with clamping grooves and adjusting grooves therein; bars in said clamping grooves and rods in said adjusting grooves; independent means on said frame for moving said bars horizontally and said rods vertically.

5; A stencil frame having bottom rails with clamping grooves and adjusting grooves therein; clam'plng means in said eiamping grooves; rods in said adjusting grooves; top

raiils fixed to said frame and engaging said PO 8.

6. A stencil frame having bottom rails with clamping grooves and adjusting grooves therein; clamping means in said clamping grooves; rods in said adjusting grooves; top rails fixed to said frame and engaging said rods and protecting stripsa-ttaehed to said frame.

7.. A stencil frame comprising a rectangular base frame with laterally extended bottom rails having adjusting grooves therein and clamping means thereon; flexible rods insaid adjusting grooves; top rails fixed to Said frame and having adjusting means at intervals engagingsaid rods; and a screen on said. frame having flaps folded over the sides of said bottoni rails, beneath said rods. and engaging said clamping means.

8. A stencil frame comprising a rectangular base frame with laterally extended bottom rails having clamping and adjusting grooves therein; bars in said clamping grooves; screws threadedvin the side walls of said clamping grooves and engaging said bars; flexible rods in said adjusting grooves; top rails fixed to said frame having screws therein at intervals engaging said rods.

In testimony whereof I have hereunto set my hand this 19th day of March, 1930.

JAMES FLOCKHART. 

